Heterocyclic endo alicyclic end capped resins

ABSTRACT

RESINS HAVING HIGH TEMPERATURE STABILITY CAN BE MADE BY CURING CHEMICALLY STABLE ALICYCLIC ENDO END CAPPED AROMATIC PREPOLYMERS. THE PREPOLYMERS CAN BE MADE FOR REACTING PROPER STOICHIOMETRIC AMOUNTS OF AN AROMATIC DICARBOXYLIC DERIVATIVE WITH A POLYFUNCTIONAL SUBSTITUTED AROMATIC AMINE, SUCH AS A TETRAAMINE, DITHIOLDIAMINE, OR A DIHYDROXYDIAMINE, AND AN END CAPPING COMPOUND HAVING THE FORMULA   1-Y2,2-Y3,3-Y4,4-Y5,5-Y6,5-Y7,6-(Z2-Z1-),6-Y1,1,4-(-X-)-   CYCLOHEX-2-ENE   WHEREIN Y1-Y6, INCLUSIVE, CAN BE HYDROGEN, HALOGEN, NITRO, ARYL, ALKYL, ALKYL ETHER, OR ALKARYL; X CAN BE CARBONYL, OXYGEN, SULFUR, METHYLENE, HALOGEN SUBSTITUTED METHYLENE, ALKYL SUBSITUTTED METHYLENE, OR ARYL SUBSITUTTED METHYLENE; Z1 CAN BE AN ARYLENE RADICAL OR AN ALKYLENE GROUP HAVING 0 TO 4 CARBON ATOMS; Z2 CAN BE AN ACID GROUP, AN ACID HALIDE, AN AMINE, OR AN ESTER GROUP; AND Y7 CAN BE HYDROGEN, HALOGEN, NITRO, ARYL, ALKYL, ALKYL ETHER, ALKARYL, OR AMINO IN A STABLE COMBINATION WITH Y6. THE END CAPPING COMPOUND CAN BE SYNTHESIZED BY REACTING A CYCLODIOLEFIN WITH AN OLEFINIC COMPOUND ACCORDING TO A DIELS-ALDER REACTION.

United States Patent ABSTRACT OF THE DISCLOSURE Resins having high temperature stability can be made by curing chemically stable alicyclic endo end capped aromatic prepolymers. The prepolymers can be made by reacting proper stoichiometric amounts of an aromatic dicarboxylic derivative with a polyfunctional substituted aromatic amine, such as a tetraamine, dithioldiamine, or a dihydroxydiamine, and an end capping compound having the formula wherein Y Y inclusive, can be hydrogen, halogen, nitro, aryl, alkyl, alkyl ether, or alkaryl; X can be carbonyl, oxygen, sulfur, methylene, halogen substituted methylene, alkyl substituted methylene, or aryl substituted methylene; Z can be an arylene radical or an alkylene group having 0 to 4 carbon atoms; Z can be an acid group, an acid halide, an amine, or an ester group; and Y; can be hydrogen, halogen, nitro, aryl, alkyl, alkyl ether, alkaryl, or amino in a stable combination with Y The end capping compound can be synthesized by reacting a cyclodiolefin with an olefinic compound according to a Diels-Alder reaction.

BACKGROUND OF THE INVENTION The present invention relates to stable, high temperature aromatic resins. Resins, according to this invention, are produced by a pyrolytic polymerization of prepolymers having reactive terminal groups. Pyrolytic polymerization is the coreaction of the reactive groups located at the terminal ends of the prepolymer upon heating at elevated temperature to cause chain extension and crosslinking of the prepolymer segment.

Polyimide resins have been produced by the pyrolytic polymerization reaction of a polyimide prepolymer having end caps of bicyclo(2.2.1)hept--ene-2,3-anhydride as disclosed in US. Pat. 3,528,590. The polyimide prepolymer was produced by reacting a diamine with a dianhydride and capping the chain with a monoanhydride having the structure:

where R is hydrogen or an alkyl group.

Synthesis of compounds similar to the alicyclic endo compounds used herein have been disclosed by Diels and Alder in US. Pat. 1,944,731. These compounds are produced by reacting a diene with a dienophile to produce a six membered ring compound. I

SUMMARY 01 THE INVENTION The high temperature aromatic resins of this invention are produced by reacting a polyfunctional aromatic diamine compound with an aromatic dicarboxylic derivative and end capping the polymer chain with a substitute alicyclic endo compound. The polyfunctional substituted alimatic diamine may be a tetraamine where the polyfunctional substituents are the four amino groups, a dithioldiamine where the polyfunctional substituents are the two amino and the two thio groups, or a dihydroxydiamine where the polyfunctional substituents are the two hydroxyl groups and the two amino groups. The polymer chain which is produced by reacting stoichiometric amounts of the diacid and polyfunctional diamine is end capped with a substituent alicyclic endo compound having the formula:

wherein Y -Y inclusive, may be selected from hydrogen, halogen, nitro, aryl, alkyl having 1 to 6 carbon atoms, alkyl ether having 1 to 6 carbon atoms, or alkaryl; X may be selected from any of carbonyl, oxygen, sulfur, methylene, halogen substituted methylene, alkyl substituted methylene, or aryl substituted methylene; Z is an arylene radical or an alkylene radical having 0 to 4 carbon atoms; Z may be selected from any of:

H O O 0 0 O -NH ,C-F, 3Cl,( J-Br,( 3-I, -(30H, ,oR where R is a monovalent aliphatic or aromatic radical; and Y can be selected from any of hydrogen, halogen,

nitro, aryl, alkyl, alkyl ether, alkaryl, or amino.

The end capping endo compound is produced by a Diels-Alder reaction wherein a cyclodiolefin having a formula:

Y2 Y3C=(!l Y5 wherein Y Y inclusive, may be selected from any of hydrogen, halogen, nitro, aryl, alkyl having 1 to 6 carbon atoms, alkyl ether having 1 to 6 carbon atoms, alkaryl; and X may be selected from any of carbonyl, oxygen, sulfur, methylene, halogen substituted methylenealkyl substituted methylene, and aryl substituted methylene is reacted with an olefinic compound having the formula:

lfi Y1 Y1C=( jZ1Z wherein Y may be selected from any of hydrogen, halogen, nitro, aryl, alkyl having 1 to 6 carbon atoms, alkyl ether having 1 to 6 carbon atoms, alkaryl; Y may be selected from any of halogen, nitro, aryl, alkyl, alkyl ether, alkaryl, and amino; Z is an arylene radical or an alkylene radical having 0 to 4 carbon atoms; and Z may be selected from any of:

u i i 0 NH;, o1 -o-o1, C-Br, 3I, G -OH, lOR

where R is a monovalent aliphatic or aromatic radical.

The prepolymers of this invention may be made by reacting a diacid with a tetraamine, a dithioldiamine, or a dihydroxydiamine and end capping the prepolymer with 3 4 an alicyclic endo compound. The prepolyrner which may a dry or slightly tacky prepolymer. The savings in cleanup be produced by the reaction of the diacid with a tetratime and materials is substantial without sacrifice of prodamine may be illustrated ideally as follows: uct properties.

N N N r R C-R"C R \Q Y1 Y7 R' Rm Ru! Ru where X, Y1Yq, and 2, have been previously identified, Alicyclic endo end cap compounds are synthesized by R is a tetravalent aromatic radical, R" is a divalent aroreacting a cyclodiolefin having the formula: matic radical, R' is hydrogen or a monovalent aliphatic 15 Y3 Y radical having 1 to 4 carbon atoms, and the n is an ini 4 teger from 1 to 20.

If the proportions of the ingredients are reversed and an alicyclic endo diamine compound is used for the end :0 cap, the prepolymer may be illustrated ideally as follows: 20 if N Y R" R' R 6 \gwherein X, Y1-Y1, Z R, R", and R may be the same wherein Y Y inclusive, may be selected from any of as in the prepolymer illustrated above. 3 hydrogen, halogen, nitro, alkyl having 1 to 6 carbon Where the dihydroxy amine is reacted with the diacid atoms, alkyl ether having 1 to 6 carbon atoms, or alkaryl; and end capped with an alicyclic endo mono acid, the and X may be selected from any of carbonyl, oxygen, sulprepolymer may be illustrated ideally as follows: fur, methylene, substituted methylene, alkyl substituted N 2 Y Y Y Y,

x Y O 0 0 0 Y. 2 7 t where R, R", X, Y -Y Z and n are the same as set methylene, or aryl substituted methylene, with an olefinic forth for the drawing above. compound having the formula:

Where an aromatic dithiol diamine is reacted with an Y8 Y1 aromatic diacid and end capped with an alicyclic endo l l Z mono acid, the prepolymer may be represented ideally as Y (J C-Z follows: wherein Y and Y is selected from the same groups repre- RLC s s s where R, R", E, E and n are the same as set forth in sented by Y Y Y is selected from the same groups as the drawing above. represented by Y -Y and additionally, may represent an amido radical; Z is an arylene radical or an alkylene radi- DISCLOSURE OF THE INVENTION cal having 0 to 4 carbon atoms; and Z may be selected High temperature resins can be made by curing pref any f;

polymers prepared by reacting stoichiometric amounts of an aromatic dicarboxylic acid with a polyfunctional sub- 0 0 0 0 0 0 stituted aromatic diamine and end capping the prepoly- -L g i5 l mer with an alicyclic endo compound. The prepolymers are characterized in that they are shelf-stable solids: which where R is a monovalent aliphatic or aromatic radical, react through the alicyclic endo compound to form a polyand 2- Ideally, the reaction y be represented as mer having good properties in the temperature range of l 280370 C. One of the chief advantages of these resins, Y in addition to their excellent physical and thermal prop- 2 erties, is the relative ease with which laminated or molded @1 6 Y Y l g Z Z 1 a 1- 2 articles may be fabrlcated from them. Thus, rather than 0-21-2 1| fabricating articles from a liquid resin, fabricators may J: L I T form the solid prepolymers of this invention from the =g Y, Y

liquid starting materials and fabricate the articles from wherein Y Y X, Z and Z have been identified above.

TABLE I The reaction as carried out is a liquid solvent, such as furane benzene, and temperatures of the reaction may range cyclopentadieneone from room temperature to about 200 F. 3,4-diphenylthiophene Special note should be made of the alicyclic endo di- 5 cyclopentadiene amine compound because it can be synthesized, for in-' methylcyclopentadiene stance, by Curtius reaction, rather than by Diels-Alder 1,1,2,3,4,S-hexachlorocyclopentadiene reaction. According to the Curtius reaction, an alicyclic endo diacid or derivative is reacted with ammonia or hy- The p f p provldefi a f y 3 E drazine according to the following reaction: 0 anve o 8 mo f p S W are Sm a e or 1 reaction to produce the alicyclic endo end cap compound. a

I Yr 001 1 d TABLE II N X m g Y I C oc1 -met y acry 1c aci Ye cinnamlc acid crotonic acid I 2,3,3-trichloroacrylic acid Y1 c N One of the resins according to this invention may be Y I produced by reacting proper stoichiometric amounts of 4 Y 2 an aromatic tetraamine with an alicyclic endo mono acid 5 at temperatures ranging from about 10 C. to about 200 Y: Y Y: Y C., and subsequently, or simultaneously, the mixture is Y I N=C= HO Ya z reacted with an aromatic diacid in the presence of a X X dehydrating agent at temperatures ranging from about I /Ye N131 -18 C. to about 200 C. The reaction may be illustrated ideally as follows:

HN NH & E R R" Y Y 2 a NH R" 2 +HOOC-R'-COOH N NH Y R R Y ",QH H9,,QH H0 Y .z;t-N R N-(F- R-CN N-tz, 1 y HN \NH HN \NH Y Y 4 Y R R" R" R W Y Y5 n 5 Y N N 4- Y? R' u:

wherein Z Y Y- and X have been previously identified. R is a tetravalent aromatic radical, R" is a divalent aromatic radical, R' is hydrogen, a monovalent aliphatic radical having 1 to 6 carbon atoms, or a monovalent aromatic radical, and n is an integer from 1 to 20. The end cap compounds may be the same or difierent trivalent alicyclie endo mono acids or derivatives. As an alternative, up to about 50% of the alicyclic endo mono acid can be replaced by acrylic acid which, in elfect, would produce a prepolymer having acrylic acid as one of the end capped groups.

Closure of the imidazole ring is effected by dehydrating in situ, i.e., simultaneously with the reaction of the constituents. The ring closure and prepolymer formation reactions must be carried out at temperatures below the polymer reaction temperature, i.e., below about 230 C.

Dehydrating agents used to facilitate the ring closure in the prepolymer reaction may be selected from organic anhydrides, such as acetic anhydride, and also, inert moisture adsorbing agents such as molecular sieves. Organic dehydrating agents are preferred because of their case of removal from the resin product of the dehydration reaction.

By adjusting the proportions of the tetraamine and the diacid, and end capping with an alicyclie endo diamine instead of a mono acid, a prepolymer may be synthesized having the following structure:

wherein the Rs are the same as disclosed above.

While the prepolymers may be synthesized from any aromatic tetraamine and aromatic diacid, the compounds must be capable of reacting together and must remain stable at about 370 C. once they have reacted. Examples of several specific compounds are listed in the following tables.

Typical aromatic tetraamines which may be used in this invention are:

TABLE III 3,3-diaminobenzidine l,2,3,5-tetraaminobenzene 3,3',4,4-tetraaminodiphenyl ether 3,3,4,4'-tetraaminodiphenylmethane 3,3,4,4-tetraaminodiphenyl sulfone 3,3 ,4,4'-tetraaminobenzophenone 2,3 ,6,7-tetraaminonaphthalene 2,3,5 ,6-tetraaminoindene 3,3 ,4,4'-tetraaminodiphenylethane 3 ,3,4,4-tetraaminodiphenylpropane Typical aromatic diacids which may be used in the practice of this invention are:

TABLE IV phthalic acid phthalic anhydride isophthalic acid N-zi isophthalic anhydride terephthalic acid terephthalic anhydride bibenzoic acid bibenzoic anhydride 2,6-naphtha1ene dicarboxylic acid 2,6-naphthalene dicarboxylic anhydride It should be understood that esters and half esters of the above acids and anhydrides listed in Table IV will be equally as suitable for use in the present invention. The ester and half ester substituents may be selected from aromatic, e.g. phenyl, or aliphatic, e.g. 1 to 4 carbon atoms, groups. As used in this context, the expression ester means that all carboxylic acid groups have aromatic or aliphatic substituent groups, While half ester means that only half of the carboxylic acid groups have aromatic or aliphatic substituent groups.

Other prepolymers of this invention can be made by reacting an aromatic diacid with an aromatic dihydroxydiamine and end capping with an alicyclic endo monoacid. The polyoxazole prepolymers which are produced are synthesized in the same manner as the polyimidazole prepolymers discussed above except that an aromatic dihydroxydiamine is employed as a constituent in the reaction rather than an aromatic tetraamine. The prepolymer may be represented ideally as follows:

wherein Z Y -Y R, R", X, and n have been identified above.

Although any aromatic dihydroxydiamine may be used to make the prepolymers of this invention, the same considerations applied to the tetraamine and the diacid above, must be made. The following table sets forth several specific examples of suitable compounds.

Typical aromatic dihydroxydiamines suitable for this invention are:

TABLE V 2,4-dihydroxy-m-phenylene diamine 3,3-dihydroxybenzidine bis(3-hydroxy-4-aminophenyl)methane bis(3-hydroxy14-aminophenyl) ether 2,3-aminomethyl-1,4-butanediol A prepolymer similar to the polyoxazole discussed above, may be made by substituting an aromatic dithiol diamine in place of the aromatic dihydroxydiamine. Thus, the prepolymer may be synthesized by reacting an aromatic dithioldiamine with an aromatic diacid and an allcyclic endo monoacid to produce the following prepolymer:.

wherein Z Y1Y7, R, R", and n have been identified linking agents for purposes of this invention are tetraabove. An alternate way of illustrating the above disphenylcyclopentadiene, maleic acid and derivatives, cmclosed prepolymer formulae is: namic acid, and stilbene. In addition to the gaseous, liquid,

Y2 Y Z l I Y o o o 6 Y4- Y, 7,

wherein X, Y -Y Z R, R", and n have been preor solid crosslinking agents, crosslinking sites may be built viously identified and G is defined as O, S-, or into the polymer chain by the use of polymer reactants having olefinic substituents; for example, a polyimidazole Ill, made from stilbene tetraamine or p-carboxy cinnamic acid. Furthermore, it should be readily apparent to those Where has been Pfevlollsly definedskilled in the art that various combinations of the above While any aromatic dithiol diamine will be suitable for li ki agents may b used Preparation of these P P Y the Same eensidefetiohs The following examples are illustrative of the proceapplied to the tetraamine and the diacid above, must be made. Several suitable representative dithiol diamines which may be used are: EXAMPLE I Approximately 3.8 grams of 2,3,4,5-tetraphenylcyclo- TABLE VI pentadiene dissolved in 7 grams of benzene. Approximately 0.8 gram of acrylic acid is added to the solution dures used to practice this invention.

2,4-dithiol-m-phenylene diamine 3,3-dithi01he11ZidiI1e and mixed thoroughly. The solution is warmed slightly and his(3-thi01-4-amih0PheflY1)methane allowed to stand for 12 hours. Crystals of 2,3,4,5-tetrabis(3amino-4-thiolphenyl)methane phenyl-2,S-endooxo-tetrahydrobenzoic acid precipitate 2,3-aminomethyl-1,4-butanedithiol from the solution.

Reaction of the prepolymer to form the polymeric prod- EXAMPLE II uct occurs through the alicyclic endo end capping cOm- Approximately 4.6 grams of 2,3,4,5-tetraphenyl-2,5- pounds. While the exact mechanism of the polym ri endooxotetrahydrobenzoic acid, approximately 2.2 grams reaction is not known, it is postulated that a three-dimenof 3,3'-di mi ob nzidine, nd approximately 2.0 grams sional polymer is formed when the prepolymer S Subof phthalic acid chloride are slurried in 300 ml. of dijected to temperature from approximately 230 C. to 370 methylformamide Approximately 20 grams of eti an- C. for up to 4 hours. Although it is not necessary for hydride is added to the solution. The resulting mixture is cure, it has been discovered that the application of up to stirred for 3 hours to give a solution of amide-acid pre- 700 atmospheres is beneficial in removing voids with the polymer. The dimethylformamide varnish is stripped of resultant improvements in product properties. The Cur solvent by evaporation on a rotary evaporator under times, temperatures, and pressures are variables which 40 vacuum at 150 C. to give a dry powder. A ceramic dish depend on the composition, mass, and shape of the arcontaining the powder is placed in an oven at 350 C. for

ticle being produced. For example, the cure for a large 30 minutes and then cooled to room temperature. A

mass of neat resin may require a lower temperature apbrown, rigid, foam-like polymer is formed.

plied for a longer period of time at a higher pressure in order to avoid cracking, incomplete consolidation, or EXAMPLE In voids, than a thin im regnated glass laminated article or a small article ooni aining up to 80% by weight of Approxlmately of 23435-tetraphenyL25- inert fillers such as inorganic salts metals or other comendooxoti-atrah-ydmben-Zmc apprpxlmately grams mon finer materialsgfglphthglrilc 51:1(1 cbheloncile, and aptpiroximlately 2.2 gramggg 1y oxy nzi ine aretoroug ymixe in y preferreii t h groups used ml. of dimethylformamide. Approximately 20 grams of prepo ymers of this invention constitute only the alih d dd d t th t Th cyclic endo compounds, it has been found that up to about gee w an a i a e o e mm e mlxture one half of the alicyclic endo compound can be replaced prlgcesse a i i -i i set firth m Examp 1e by acrylic acid without materially altering the properties 8 0amp0 ymer 18 formed upon of many of the polymers. Ideally, this provides a pre- 55 curing t e prepo ymer Pow polymer with an acrylic acid radical end cap at one end EXAMPLE IV of the prepolymer chain and an alicyclic endo end cap at the other. Approximately 4.5 grams of 2,3,4,5 tetraphenyl-2,5-

In order to enhance product properties, crosslinking endooxotetrahydl'obehloie acid, approximately grams agents may be incorporated into the polymer chain. Solid of phthalic acid Chloride, and approximately grams or liquid organic compounds having olefinic unsa'thra- 0f 3,3'-dithi01hehZidi11e are mixed in approximately 300 tion can be added to the initial starting materials while of dimethylfofmamide- The mixture is Processed in gaseous organic olefins are introduced into the starting the Same manner as Set forth in EXamPIe U above- The material by reaction under pressure up to about 3000 p.s.i. prepolymer powder formed a rigid foam p Normally, an amount of crosslinking agent equivalent up We Claim:

to 10% by weight of resin at initiation of cure is used. A method of making a p p y comprising Specific examples of a few of the gaseous olefinic comacting in The Presence of an Organic Solvent P p pounds which are suitable crosslinking agents are ethyl- Stoiehiometrie amounts f ene, propylene, halogenated ethylene, halogenated propyla tetfafhhetional aromatic diamine Compound ene, and halogenated butadiene. Specific examples of wherein the two additional functional groups are seliquid olefinic compounds which are suitable crosslinking lected from the group consisting of dithiol, dihyagents are styrene, cyclopentadiene, furane, crotonic acid, droxyl, and diamine;

acrylic acid and halogenated, phenyl substituted, or meth- (B) an aromatic dicarboxylic compound selected from yl substituted forms thereof. Specific examples of a few the group consisting of acids anhydrides, esters and of the solid olefinic compounds which are suitable crosshalf esters;

(C) an end cap compound comprising a substituted alicyclic endo compound having the formula:

6. A method of making a prepolymer according to claim 1 wherein an olefinic crosslinking agent is added.

Y zl-z,

ll X 5 7. A heterocyclic thermosetting prepolymer having the Y, Y Y1 formula 2 N N Y Y Y! 3 I l 2 Y 0 e c G Y Y 4 Y Y5 6 7 6 Y5 to give a prepolymer having 1 to 20 repeating units, wherein Y Y inclusive, is selected from the group consisting of hydrogen, halogen, nitro, aryl, alkyl having 1 to 6 carbon atoms, alkyl ether having 1 to 6 carbon atoms, and alkaryl; X is selected from the group consisting of carbonyl, oxygen, sulfur, methylene, halogen substituted methylene, alkyl substituted methylene, and aryl substituted methylene; Z is selected from the group consisting of an arylene radical and an alkylene radical having 0 to 4 carbon atoms; Z is selected from the group consisting of where R is a monovalent aliphatic or aromatic radical, and --NH and Y; is selected from the group consisting of hydrogen, halogen, nitro, aryl, alkyl having 1 to 6 carbon atoms, alkyl ether having 1 to 6 carbon atoms, alkaryl, and amino; in a temperature range of 10 C. to about 200 C.; and

(D) dehydrating at temperatures ranging from -18 C. to about 200 C.

2. A method of making a prepolymer according to claim 1 wherein up to one-half of the end cap compound is replaced by acrylic acid.

3. A method of making a prepolymer according to claim 1 wherein the substituted alicyclic endo compound is bicyclo (2.2.1)hept-S-ene-Z-carboxylic acid.

4. A method of making a prepolymer according to claim 1 wherein the substituted alicyclic endo compound is bicyclo(2.2.1)hept-5-ene-2,3-diamine.

5. A method of making a prepolymer according to claim 1 wherein the carboxylic compound is selected from the group consisting of aromatic diacids, aromatic anhydrides, aromatic ester, aromatic half ester, aromaticaliphatic ester having 1 to 4 carbon atoms in the aliphatic radical, and aromatic-aliphatic half ester having 1 to 4 carbon atoms in the aliphatic radical.

wherein Y Y inclusive, is selected from the group consisting of hydrogen, halogen, nitro, aryl, alkyl having 1 to 6 carbon atoms, alkyl ether having 1 to 6 carbon atoms, and alkaryl; X is selected from the group consisting of carbonyl, oxygen, sulfur, methylene, halogen substituted methylene, alkyl substituted methylene, and aryl substituted methylene; Z is selected from the group consisting of an arylene radical and an alkylene radical having 0 to 4 carbon atoms; Y, is selected from the group consisting of hydrogen, halogen, nitro, aryl, alkyl having 1 to 6 carbon atoms, alkyl ether having 1 to 6 carbon atoms, alkaryl, and amino; R is a tetravalent aromatic radical; R" is a divalent aromatic radical; G is a divalent radical selected from the group consisting of -O-, -S, and

where R' is hydrogen or a monovalent aromatic or aliphatic radical; and n is an integer from 1 to 20.

8. A propolymer according to claim 7 wherein one of the end cap compounds is replaced by acrylic acid.

9. A prepolymer according to claim 8 wherein the end caps are bicyclo(2.2.1)hept-5-ene-Z-carboxylic acid radicals.

10. A prepolyrner according to claim 7 wherein the formula is 11. A prepolymer according to claim 7 wherein an olefinic crosslinking agent is added.

12. A resin product comprising curing the prepolymer of claim 7.

13. A resin product comprising curing the prepolymer of claim 8.

14. A resin product comprising curing the prepolymer of claim 10.

15. A resin product comprising curing the prepolymer of claim 11.

References Cited UNITED STATES PATENTS 3,528,950 9/1970 Lubowitz 2 6078.4 3,316,213 4/1967 Berr 26047 1,944,731 10/1933 Diels et a1. 260-3466 1 JOSEPH L. SCHOFER, Primary Examiner I. KIGHT, Assistant Examiner US. Cl. X.R. 

